Does PC2100 ram work in a T41?

[dorronto]

I read that even though a T41 uses PC2700 ram, it will also work with PC2100 ram. This is from an IBM T41 Offering Announcement on the web. Just curious..........................

Anyone do this?

Thanks,
Ron

[RealBlackStuff]

If it is the same layout as the 2700, it should work, but at a much slower speed.
If you mix 2700/2100, they will both run at 2100 speed.
Avoid if you can, unless you don't have the 'need for speed'.

[dorronto]

Thanks. I've read that there isn't that much diifference anyway between 266mhz and 333mhz. I believe the laptop will be fast enough anyway.

Anyone agree?

Ron

[GnatGoSplat]

I never really ever noticed any difference between faster/slower memory.

If you like tweaking and playing around with hardware, you could always try overclocking the RAM to see if it's stable at 333MHz. You would have to modify the SPD to make the RAM think it's PC2700. Instructions here:
http://www.thetechrepository.com/showthread.php?t=57

Then run MEMTEST86 overnight or so to see if the RAM is stable when overclocked.

I used to overclock the DDR in my desktop machines and they almost always worked perfectly one step faster (couldn't go from 2100 to 3200 but to 2700 was okay). It was easier on the desktop machines though, the BIOS supported memory overclocking so no tweaks to SPD required.

[cmarti]

Thanks. I've read that there isn't that much diifference anyway between 266mhz and 333mhz. I believe the laptop will be fast enough anyway.

Anyone agree?

Ron

Ron,

The T41 comes from factory with PC2100 installed just my X31, there is no difference if you have a banias cpu installed in your lappy.

[dorronto]

Thanks Carlos. That's what I thought...............

Ron

[kryptonpwx]

Thanks. I've read that there isn't that much diifference anyway between 266mhz and 333mhz. I believe the laptop will be fast enough anyway.

Anyone agree?

Ron

Ron,

The T41 comes from factory with PC2100 installed just my X31, there is no difference if you have a banias cpu installed in your lappy.

In my opinion, even with Banias CPU, PC2700 and PC2100 will make a difference, though a 25% in memory bandwidth will not result in a considerable differece.

My reasoning is as follows. Assume the ideal memory bandwidth requirement is proportional to CPU FSB.

Theoretical memory bandwidth:
PC2100 - DDR266 - 2100 MB/s
PC2700 - DDR333 - 2700 MB/s
PC3200 - DDR400 - 3200 MB/s
* Dual channel should double the value

Ideal matching memory configuration without waste:
Celeron4 400FSB - Dual DDR200
Pentium4-B 533FSB - Dual DDR266
Pentium4-C 800FSB - Dual DDR400

According to this guess, I make some bandwidth benchmark on some machines.

Celeron4 400FSB (Dual channel DDR400 @ 266) - 2562 MB/s (Dual channel DDR266 should provide 4200 MB/s bandwidth, CPU FSB is the bottleneck)
Pentium4-C 800FSB (Dual channel DDR400 @ 400) - 4711 MB/s (Dual channel DDR400 should provide 6400 MB/s bandwidth, chipset is the bottleneck)

Since all 855PM based mobile CPUs are 400FSB and single channel memory, the ideal memory is DDR400. Whether putting in DDR266 or DDR333, the deserved theoretical memory bandwidth will be revealed. Some results.

X31 DDR266 - 2017 MB/s
T41 DDR333 - 2588 MB/s

Similarly, for DDR2 based platform, provided the high frequency of DDR2, dual channel is not as necessary as in DDR's case, esp. for mobile CPU.

Ideal matching memory configuration without waste:
Dothan FSB533 - Single DDR2 4200
Memrom FSB667 - Single DDR2 5300

So for 915GM and 945GM, enabling dual channel will not bring a noticable memory bandwidth increase.

* Dual channel will speed up integrated video a lot, though.

In the above, only memory bandwidth is discussed. In pratical use, the difference between DDR266 and DDR333 in T41 will not be conceivable. Though T40 only supports DDR266, the performance difference between T40 and T41 is little.

[chicomark]

Yes, I had 2100 and 2700 installed at the same time (two sticks of 256) and it worked fine, but in this case the machine will run at the slower speed

Mine is a T41 2373-1FM

[dorronto]

Thanks to all for your experiences in this situatuion.........

Ron